Origin of the Joint Chiefs of Staff

At the beginning of WWII, President Roosevelt created a committee of
U.S. staff commanders to coordinate operational strategy for the armed
services. It was established as the American component of the Combined
Chiefs of Staff of Great Britain and the United States, which prepared and
implemented Allied strategy. The group became known as the U.S. Joint
Chiefs of Staff. The members of the new JCS were the counterparts of the
British Chiefs of the Army, Navy, and Royal Air Force.

The first members of the JCS were Adm. William D. Leahy, President
Roosevelt's special military advisor, with the title of Chief of Staff to
the Commander in Chief of the Army and Navy, who presided over the JCS;
Gen. George C. Marshall, Chief of Staff of the Army; Adm. Ernest J. King,
Chief of Naval Operations and Commander in Chief of the U.S. Fleet; and
Gen. Henry H. Arnold, Deputy Army Chief of Staff for Air and Chief of the
Army Air Corps. Each member was promoted to five-star rank in December
1944, when the new grades were established.

The National Security Act of 1947 formally established the Joint Chiefs
of Staff and laid the foundation for a series of legislative and executive
changes that produced today's defense organization.